From the Vault: Cambrian Monster Mash

Welcome to the ocean of monsters. In this classic episode of the Stuff to Blow Your Mind podcast, Robert Lamb and Joe McCormick travel back 500 million years to the monster-haunted waters of the Cambrian period. Meet the monstrous trilobite, anomalocaris, opabinia, hallucigenia, wiwaxia, pikaia and leanchoilia. Plus, Dr. Anton Jessup drops by for a visit. (Originally published Oct 19, 2017) 

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Episode Transcript

Speaker 1 (00:05):
Hey, you welcome to stuff to blow your mind. My
name is Robert Lamb and I'm Joe McCormick. And it's Saturday.
Time to venture into the vault for an exploration of
the Cambrian era. Oh yes, this is an exciting one.
This one published just last year October. That's right, And
so this was going to be an episode about Cambrian
monster was going to be It was one, definitively say,

(00:27):
it is one about about Cambrian animals and and their
their monstrous characteristics, and about evolutionary biology. We get into
some interesting theories about what caused the so called Cambrian explosion.
So this was an October episode. We're running it in November.
Are we cheating a little bit? We extending the October? Oh? Yeah,
we're doing a little Halloween hangover, little Halloween hang around.

(00:48):
I don't know that Halloween gets gets to last until
the coming of Crampus in my book. So okay, haven't
we Ultimately we have another month or so that we
can continue to to dip into the monster bucket here. Um,
I do want to say on this particular episode, we
also have some merchandise to go along with it. We
have a fabulous new logo design which takes our existing

(01:11):
logo the sort of abstract symbol that you associated with
Stuff to Blow your Mind, and it positions it within
uh kind of a Cambrian sea of strange life forms.
And that logo is available on a shirt, on a throat, pillow,
on a sticker, UH, you name it. You can get
it through our t public store. There's a link for
that at the top of our homepage. It's Stuff to

(01:32):
Blow your Mind dot com. And if you're looking at
this particular episode on our website, there you'll also see
that image front and center as the lead image for
this episode. Can you get it engraved on a belt buckle?
They do belt buckle. I don't know if they do
belt buckles yet, but it's probably. There's there's a lot
of of of possibility. You can do hoodies, you can
do like various types of shirts. And I bring this up,

(01:53):
I mean mainly because it's fun and it's a great
way to share Stuff to Blow your Mind and the
stuff to Blow your Mind message, I guess you would say,
with everyone. But it's also a great way to support
the show, UH. Spending a little money on some cool
merchandise that is kind of a kind of a wink
to other folks who may be listening as well. Alright, well,
with that, i'd say let's jump right into our episode
on the Cambrian Monster Mash. Hello Dr jessup, anybody here? Well, hello,

(02:27):
good sir. I'm glad to see you have arrived. I
apologize I can't be there to greet you in person,
but please know that I am most appreciative of your attendance.
It's so hard to find good volunteers these days. It's
it's just if every undergraduate rely even a bit of
backbonus simply vanished in the past six months. Huh okay,

(02:50):
So am I in the right place? Ah? Well, well,
perhaps instead you should ask whether you were in the
right time. Uh well, the flyer said, you doing SIUR
for test subjects in something called Middle Cambrian exposure. I'm
not sure what that is, but if you're paying cash,
I'm still on board. Excellent. Now tell me do you

(03:13):
have any experience with time displacement? I don't think so,
of course not, of course not. And tell me can
you swim? You know I can, but it's one of
those things I wouldn't say. I'm a great swimmer. Nobody's perfect.
Do you see the throbbing light lucifortex in the center

(03:35):
of the room or well, yeah, yeah, I do, excellent,
go to it all right? Yes, yes, closer, closer? Doesn't
feel right? What's that feeling? What's the matter, my little vertebrate?
Haven't you ever wanted to feel? Five hundred million years younger?

(03:57):
What is that? Is that? An ocean? Oh? My god,
it's like the whole planet's an ocean. It's full of monsters.
Welcome to Stuff to Blow your Mind from how Stuffworks
dot Com. Hey, welcome to Stuff to Blow your mind.

(04:25):
My name is Robert Lamb and I'm Joe McCormick and Robert.
That was obviously a reference to some kind of journey
we may be taking to the Cambrian period. That's right. Yeah,
we had a little cameo by the late great Anton
Jessa late did he die? I don't know. I mean
there there are rumors of his death, but who knows
for sure? That always exaggerated, is well? Anyway, today, I've

(04:45):
got a little story I want to tell to lead
us into our topic. Now. Obviously it is October. It's
our favorite time of year to talk about monsters. We
talked about monsters anyway, but this is the time where
we really double down. It's clear mandate for monsters. And
I got to take a monster science It's adventure this
past month. So this this past month, early on one
Sunday morning, my wife Rachel and I were in Canada

(05:07):
and we woke up before dawn on this Sunday morning
in the town of Golden British Columbia. It's in western Canada,
the Canadian Rockies, and we had some coffee and bagels,
and we filled up our backpacks with a bunch of
layers of warm clothes, bottles of water, all that hiking stuff,
and we drove along the steep mountain sides to this
tiny town called Field in British Columbia. And there we

(05:30):
parked beside a gas station and we waited to meet
our guide and the rest of this tour group. So
the guide was a paleontologist named David, and the hiking
group was mostly French speaking families, some really lovely people
and some very intelligent children with great questions like why
do animals die? Uh? And so we hiked through the

(05:51):
town of Field and along this uphill path through the
forest up the side of Mount Stephen, and as we
went on throughout the day, the trail got steeper and steeper,
and we could see through the trees. The town we
came from was becoming this tiny miniature model in the distance.
And then right around midday we came out of the
tree line and we walked up on this bare plane

(06:12):
of flat rocks and they were pieces of the underlying
shale formation that had chipped and broken off, and they
gathered in this relatively flat part of the mountain side.
And on this plane of rocks, you walk around and
you pick up these mineral fragments and they're full of fossils.
It's just fossils everywhere. Almost every other rock you find

(06:33):
has the shape of an animal from millions of years
ago printed into it. You're literally walking on thousands and
thousands of fossils. So you're in this this mountainous environment
and David, who by the way, i'm picturing as the
Android from Prometheus and Alien Covenant, is guiding you and
showing you these these prehistoric remnants in the rock. David

(06:55):
was not Michael Fastbender, but David was excellent. He was
a really, really good guy. And this place we came
to where we were walking on fossils. This was the
Mount Stephen Trial Bye beds. It is a graveyard of
organisms from the Cambrian Period about five hundred million years ago. Now.
Mount Stephen is in an area that's home to the
Burgess Shale geological Formation, which is one of the most

(07:18):
important sites of Cambrian Period fossils in the world. And
if you ever get a chance to do one of
these hikes, I highly highly recommended. I think it literally
might be the coolest thing I've ever done. You have
to book them through this organization called the Burgess Shale
Geoscience Foundation, and they pair you with a guide. Our guide, David,
the paleontologist, was an excellent science communicator. He was really

(07:39):
good with the kids on the group, and he was
a great hiking guide. So if you get a chance
to go with David, big thumbs up to him. Be
warned if you do try to do this, it's a
tough hike. It's like eight kilometers round trip horizontally with
a seven hundred and ninety five meter elevation gain, which
is like two thousand, six hundred feet, and and that's

(08:00):
starting at like twelve hundred or hundred meters of elevation
at the at the base of the mountain. Uh So,
the air is thin, and it's worth doing some other
hikes at higher elevation to get yourself accustomed to the
lack of oxygen. But I also don't want to scare
you too much, obviously I will. I am no kind
of athlete or experienced altitude hiker or anything like that,

(08:21):
and I survived so beer advising listeners to wear their
best flip flops on this particular Just be prepared, have
some layers, have some water, do a little practice. If
you can make the trip, it is absolutely worth it
to see these fossils firsthand. You can pick them up.
You can feel the ribs of these Cambrian organisms. You
can you can feel the contours of their bodies as

(08:42):
they printed on this ancient shale. But also it's really
cool to be there, just because the area around field,
including Mount Stephen, trial By Beds and the Burgess Shale
Quarry quarries, are just arguably the most important Cambrian fossil
sites in the world. They are a geological window in
to a time stranger I would argue than any alien

(09:04):
planet in any movie, any book, any video game, any
Star Trek episode. I think the real alien monsters. Uh.
And of course, as you if you know the show,
you know we use the term monster affectionately. It's not
a pejorative. The real alien monsters are not out there
on some exoplanet. They were right here five hundred million

(09:25):
years ago, and in this one amazing place you can
sort of crunch through their frozen graveyard and it's awesome. Now, Joe,
do you find yourself falling into the same admittedly dumb
trap that I do when I when I think about
about the nationalities that are sort of overlaid regarding fossil
uh finds like these are Canadian Cambrian monsters or something

(09:50):
like that. Like, yeah, because I was recently reading to
my son about Terra saurs and was reading about the
about about Bavarian fossils of Terra saurs, and is as
silly as it is, I couldn't help but think of
of Bavarian Terra stars thinking about the very in rhistoric creature,
like wearing later hosen the big big stein of beer.

(10:12):
And it's so unfair. You know, I've done the same
thing thinking of Mongolian fossil finds in our previous episode,
we talked about various raptors. I believe Kim remember it
was the velociraptor or dononicus. But I could not help
but then think about them in terms of like human
history regarding that area, and it yeah, part of his pack.

(10:36):
Uh yeah, yeah, I know exactly what you're talking about.
And that does highlight the need to sort of explain
how the Cambrian world was so different than our world,
not just that it had different animals in it, but
that planet Earth was different than So when I say
it was an alien planet, I mean that quite literally.
It's not just that it had different fauna, it was
a It was a totally different place to live. And

(10:59):
so before we get into exploring these monsters of the
Cambrian Period, these beautiful and bizarre creatures that you couldn't
even dream up if you tried, I think we should
take a look at the Cambrian period itself and explain
what it was like to be Terra five million years ago.
So the Cambrian Period lasted from about five hundred forty

(11:20):
to about four hundred and eighty five million years ago,
and if you were dropped from today straight into the
Cambrian period, you would not recognize planet Earth. The Earth,
for one thing, revolved faster than it does now, so
days were only about twenty one hours long, and there
were about four hundred and twenty of them in a year.

(11:40):
The air would be hot, so the average global surface
temperature would have been about ten degrees celsius hotter than today.
That's a good bit hotter. The atmosphere, while it did
have significant free oxygen, at this point, was not quite
what it is today. It would have felt a little
bit thick with carbon dioxide in your lungs. If you
happen to see dry land, it would probably look more

(12:02):
like the surface of Mars than Earth today. Because land
dwelling plants didn't exist yet. It's kind of hard to
imagine Earth that way. And without plant roots to hold
the soil in place, land surfaces eroded very easily in
the wind and the churning water. So you know, the
continents are constantly just kind of burning away into the

(12:23):
oceans and being reformed. So to call back to a
previous episode we did, was this was definitely a world
before fire. Oh yeah, because what would it what would
it burn? Right? Yeah? I mean, I can't be sure
it was totally without fire, but I mean, yeah, obviously
not fire on the scale we see of wildfires in
forests today because there was oxygen in the atmosphere at
this point. But yeah, what what would burn? What would

(12:45):
the fuel be? All Right, So we have this alien
world with just a barren land when visible, and then
we have this this ocean, this strange ocean, and the
Cambrians earth that that's not a story about land at all.
That is a story about ocean. It was the ocean
planet at that point. You could probably make the argument
it's the ocean planet right now, but it definitely was then.

(13:08):
According to Cambrian Ocean World Ancient Sea Life of North
America by John Foster uh, the level of the seas
rose steadily in this saw tooth rise and fall pattern
throughout the Cambrian period. So at the beginning of the
period sea level was actually a little bit lower than
it is today, But by the end of the Late
Cambrian sea level was about a hundred and sixty meters

(13:30):
or five and thirty feet higher than it is today.
So in today's terms, New York Underwater Rome underwater, paris underwater,
bag Dad underwater, even parts of Moscow underwater, and the
high sea level in the Cambrian led to flooding of
about forty percent of the area of Earth's continental masses.

(13:50):
Compared that to today, we're only about five percent of
that continental area is covered in water. So most of
our planets dry land mass was gathered together closer to
the south pole, and the continent that became North America
was then called Laurentia, not than called by people who
have been but people today called that continent than Laurentia.

(14:11):
And you sort of have to imagine North America turned sideways,
mostly flooded, straddling the equator. Also adding to the alien
quality in the Cambrian, astronomy would have been a little
bit different. So the Moon was more than twenty kilometers
closer to Earth than meaning that its gravity was stronger,
meaning the high and low tides on Earth were higher

(14:33):
and lower. Okay, because you know, my son was just
talking to him to me the other day about the
size of the moon and prehistoric times. Oh yeah, like
he knew that the moon was bigger in prehistoric times. Yeah,
and uh, and knows that it will be it will
be smaller in future times. Did he into it that
or did he find that out somewhere. He consumes a

(14:53):
lot of Dinosaur Train and he really likes this podcast,
Wow in the World, that's great science podcast for for kids.
So and then you know, we talked to him a
lot about science. Man, I wish I was that cool
when I was a kid. I probably just would have
told you about like which ninja turtle was bigger in
the prehistoric times? Yeah, so far Ninja turtles will probably
come in and wash it all the way. But for now,

(15:15):
he's really really into the science, like an alien ocean
driving away the continents. Okay, So if we looked under
that ancient ocean, that's where the real craziness comes in,
because we would find this vast realm of gorgeous, terrifying,
surreal monsters that would look completely unlike the kind of
Earth life we're familiar with today. Because the Cambrian period

(15:39):
is the geological layer where we see evidence of one
of the most fascinating and mysterious events in the history
of life on Earth, known as the Cambrian explosion. So explosion.
What exploded? Was this like a bunch of volcanoes or something. No,
the Cambrian explosion is a story about bio diversity. So, Robert,
how old is the Earth? Oh, it's so at four

(16:01):
and a half billion years old. Yeah, that's the general
astronomical idea. So four and a half billion years old.
We've had this planet roughly, and we know there's been
single celled life on the planet for at least maybe
three and a half billion years or so, based on
fossil traces left behind by these organisms. And new findings
keep pushing the debatable frontier of earliest life farther and

(16:23):
farther back into the darkness of Earth time. One example,
I just came across So the other day, just earlier
this year, in March, there was an article published in
Nature arguing that apparent microbe fossils in the New vo
Agatuck Belt in Quebec are about three point eight billion
and possibly four point three billion years old, somewhere in

(16:44):
that range, and these single celled life forms would have
been surviving around hydrothermal vents and had this biochemistry based
on eating and excreting iron. That's pretty rough and tumble.
That's like a comic book film, right, yeah, the iron eat.
And the crazy thing is that if these findings are correct,
life on Earth would have began within just a few

(17:06):
hundred million years of the planet first accreting together in space.
It's kind of hard to believe, but whether life on
Earth began like four point two billion years ago or
more recently, we know that for a long, long time,
life on Earth wasn't becoming much more complex, right. There
was no serious multicellular life. So no animals, no fish

(17:27):
and reptiles, no birds, no plants, no mushrooms, just microbial
organisms like bacteria and archaea floating around in the oceans,
forming mats and films and occasionally occasionally building these giant
mineral brains in the surf called stromatallites. So this would
be if this were a science fiction film, this would
be the least cinematic alien life form encounter unless it

(17:52):
made people like, you know, horribly sick obviously, or possessed them.
Biofilm planet, yeah, yeah, the Planet of Slime. Yeah. There
was the episode of of Star Trek that that does
not does not make it to to the series. Yeah,
and that's you know, that would have been the story
of Earth for most of Earth's history, not having any
kind of interesting animals or anything like that. Not to

(18:14):
say that microbes aren't interesting in themselves, but maybe less
interesting to look at. It would have been slime planet. Yeah. Generally,
this is the stuff that occupies one, maybe two pages
of a of a large prehistoric life book before you
get onto the more exciting things, the things that children
can imagine fighting each other. But it's most of the
life that's ever happened. And then billions of years later,

(18:36):
at the beginning of the Cambrian Period, something happens very suddenly.
Loads of insane animals show up. And when I say suddenly,
I have to qualify that that's suddenly from a geological
point of view, which in reality means it took millions
of years about five hundred and forty million years ago
to about five hundred million years ago. But that's still
pretty suddenly compared to the age of the Earth. And

(18:59):
this g illogically rapid spike in animal diversity delivers creatures
with bilateral symmetry, with large bodies, with eyes, with legs,
with shells, with segmented body parts. You've got all of
these crazy different types of creatures suddenly showing up, and
it's like, where did they all come from? Yeah, it's

(19:21):
like all these prototypes are rolled out at once. It's
like the segment in is it is a RoboCop one
or two where we get all the crazy prototypes that, oh,
that's a RoboCop two. Yes, yeah, it's one of our
favorite points of comparison on the show for biology. Yeah
uh yeah. You have suddenly all these different, you know,
seemingly crazy examples of life, and many of many of

(19:43):
which don't seem to to fall in easily into that
category of well, this is a precursor to something we
have later on. It's a precursor to something we have
today now. Of course, for some people with negative attitudes
towards evolutionary science, this provides some kind of rhetorical ammunition,
right indeed, I mean the explosion is often exploited by
evolution of knives. Even Darwin, we have to note thought

(20:04):
that the explosion was at odds with the normal evolutionary process,
which in a funny way could be true, but not
in the way an evolution denier would mean a couple
of thoughts. Evolution is we're familiar with it today, tends
to take place within ecosystems in which every niche is
already filled. So basically every way there is for a
creature to make a living, there's already something trying to

(20:26):
do that, So if you want to compete, you've got
to outcompete these other organisms. The global ocean of the Cambrian,
on the other hand, represented a world in which it
seems like there was still tremendous ecological opportunity to occupy,
Like there was territory in the ecology that didn't have
any existing competition. So it was a time in which

(20:47):
an animal could start doing something to eat or to
otherwise survive, and no other species was already doing that thing.
There was just sort of like free land to grab. Yeah,
like yeah, land grab call the frontier, uh, except without
other organisms already occupying it. So that there could be
one explanation for why evolution seems to be working differently

(21:07):
at this one period in history than it has since.
But also the Young Earth creationist who exploits ongoing debates
in biology to sort of resort to the supernatural. They're
employing a fallacy in rhetoric known as the argument from
ignorance fallacy, which means like I don't know what caused something,
therefore the cause is x uh example, you don't know

(21:31):
who committed the Jack the Ripper murders. Therefore it was
interdimensional sasquatches. Now the version employed here, of course, says,
you can't all agree. We don't know on what caused
the sudden or geologically sudden biodiversity of the Cambrian explosion.
Therefore the cause is supernatural. Now, this line of thinking
obviously doesn't get you anywhere once you examine it. But

(21:52):
the disagreement and debate over the cause is a fascinating,
outstanding question, and it's something I think we want to
entertain a few answers to day. Now, some of the
hypotheses are primarily environmental and chemical. Right, so some scientists
have proposed that the cause of the camera and explosion
could be a rise in the content of oxygen in

(22:12):
the atmosphere, which leads to an increase in the level
of dissolved oxygen in the oceans. Now, of course, remember
that Earth's original atmosphere did not have free oxygen, right,
that was added to the atmosphere gradually as a waste
product of photosynthesis. You have all these microbes out there
and they're eating the sunlight and then their geoengineering the

(22:32):
atmosphere with their waste products. Which included oxygen. The gradual
natural terraforming of our world. Yeah, the microbial terraforming of Earth,
which absolutely did happen in the past. And that's where
we get our oxygen. Now, when you think about it,
large fast moving animals need lots of oxygen to feed
their energy hungry tissues. Like think of the way that
when you move your muscles a lot, your body starts

(22:55):
greedily gulping down more and more air. In the same way,
if you think about these organisms in the past, suddenly
you wanted to have organisms with large bodies. They would
have needed access to oxygen. So maybe when that oxygen
became available, suddenly you could build these big, fast moving
bodies and you get all this animal biodiversity. Okay, so
previously the oxygen economy would not support this kind of growth, right,

(23:19):
But the idea is then it would. So did a
sudden increase in oxygen drive the explosion. Well, some recent
studies have cast doubt on this hypothesis, including one published
in Nature and by Spurling at all uh and it
basically did not find evidence of a significant increase of
oxygen in ocean water at the beginning of the Cambrian

(23:40):
so evidence shows that if there was an increase in
oxygen at the Cambrian transition, it was kind of a
small one. All right, Well, what else do we have? Well,
other hypotheses are more biological and ecological, Like what if
there was one type of biological innovation, some new way
for animals to make a living or new thing. Animals

(24:01):
could do that rapidly accelerated competition with an ecosystems, which
would speed up natural selection and cause new species to
form much more rapidly. How about the example of site
Oh yeah, this is a big one. Yeah, so previous
animals they might have had some kind of photosensitive spots
or receptors that would have allowed them to, for example,

(24:22):
move towards the sunlight. But the Cambrian is the first
period in history where we have evidence of complex site organs,
you know, eyes. It's the age of organisms with compound eyes.
So imagine how much adaptive pressure would be put on
you if you lived in a world where all creatures
were basically blind and then suddenly some of your competitors

(24:44):
could see. Yeah, this is this is a crazy thing
to try to imagine, but yeah, just just think of
sight coming online in a world and all the additional
stuff that this entail. Suddenly pigmentation begins to matter. I mean,
it's hard to even apply. You're one is tempted to
apply this to human arms race um, which is which

(25:04):
is often an an apt comparison. But I mean, what
can we even look to in human technology and human
weapons systems. I mean, I'm just thinking maybe you could
apply it. You can compare it to flight and say
that well, once, once human technology allowed us to take
to the air, that created an entire new theater of war,

(25:25):
and they also changed the existing theaters of war. And
I think you could make that comparison pretty well, like
flight changed the nature of warfare forever, Like suddenly just
having like lots of ground troops didn't didn't matter a
whole lot, right, But this, this seems more extensive than that.
You know, It's like it's it's the opening of another

(25:45):
dimension of competition in a way. Yeah and yeah, and
you think so you you mentioned pigmentation, Suddenly the colors
you are matter, like blending in matters. But also think
about the way it would make movement matter. We would
make the shapes of bodies matter, would just completely change
all the dynamics of how creatures interacted with one another. Yeah,

(26:06):
not only prey predator interactions, but of course just interspecies communication,
uh and as well as mating. I mean everything changes
because of this. Yeah. So we'll come back to look
at more of these answers to this question throughout the episode,
but I think we should take our first break and
then we come back. We will look at one of
the first major inhabitants of our Cambrian monster House. Thank you,

(26:30):
thank Alright, we're back. So as we roll through these,
I also want everyone to think of potential Halloween costume ideas,
because I think we have some We have some wonderful
prehistoric monsters here that I think are more inventive listeners
might be able to to turn into a mask or
a full body cost Okay, So I want you Starship
Troopers fans out there to get a little bit excited

(26:52):
about Stone Bug Planet, Okay. Fans of the book or
the movie, well, I mean they both got bugs, that's okay.
So in eight teen six, there's a Canadian geologist by
the name of Richard McConnell, and he's visiting the town
of Field, the same town I went to when I
began the walk up Mount stephen Field, British Columbia, where
some railroad workers told him they had found something creepy

(27:15):
on the slopes of nearby Mount stephen They were these
things that they called quote stone bugs, and these were
in fact trialo bytes, the best known inhabitants of the
Cambrian oceans. Now trio bytes are not a single species,
but there are a class of extinct animals from the
phylum arthur Poda, and so that would be the same

(27:37):
phylum that includes, for example, insects and crustaceans, lobsters or arthropods.
Insects and spiders or arthropods. These exoskeleton creatures now trialo bytes,
were an enormously successful form of life, beginning in the
Cambrian and surviving for about three hundred million years until
they were wiped out about two hundred and fifty million

(27:57):
years ago in the Permian Triassic extinct Shinn event, also
known as the Great Dying, which was the biggest mass
extinction in the history of planet Earth. About of all
marine species went extinct. It's kind of hard to imagine,
but until then trial bytes were like sort of like
the insects of today, just this enormously successful type of

(28:21):
creature found everywhere. They were a swarm upon the face
of the deep or I kind of want to think
of them as the infinity bugs. I like it. So
the trialo byte body structure kind of resembles like a
roly poly or a pill bug, maybe crossed with a
horseshoe crab. It's got these articulated segments lining its back
and if you look at it from the top down,

(28:42):
you'll see this flat, hard shell made of a matrix
of tiny calcite needles. And if you look at it
on the vulnerable underside, you'll see the legs and the
gills and the mouth. And actually it does kind of
look like a like a roly poly or a pill
bug on the underside too, if you ever see them. Yeah,
I have to say Trilobyte, of all the creatures were
going to discuss today, well, first of all, it's the

(29:04):
most famous, I think, so most of you have probably
seen images of it before. But it also does look
a lot more like existing creatures. It doesn't if you,
if you didn't know better, you could easily see an
image of this and think that it could be something
living today. Yeah, I think the creepiness of the trial
Bye World comes not from seeing their body plans, because

(29:27):
you can see stuff that looks kind of like them.
Like you say, it's just how many of them there were,
and thinking of this being one of the dominant body
plans on the planet, or the dominant body plan on
the planet. And if you're still drawing a blank as
to what this looks like, I'm going to include images
of of all the species that we're discussing here on
the landing page for this episode. It's stuff to blow

(29:48):
your mind dot com. Alright, so we've had a look
at the creature's legs. Let's turn this puppy around. Okay,
turn it so if you look at it from the
top down, you can basically deve via a trilobyte in
three both ways. So if you look at it lengthwise,
you're looking at head on. Lengthwise, there is bilateral symmetry,
and this is the cameraan period. We see these animals

(30:10):
with bilateral symmetry really taking over. You can fold them
in half and they're like a book. They match on
both sides. And in that lengthwise direction, the trilobyte is
divided into three lobes. You've got the axial lobe, which
runs down the middle from the head to the tail,
kind of like the spine of the book, or like
the spine of a vertebrate. And then you've got the
two plural lobes on each side which you're shielding the

(30:33):
legs from above. There were these you know, shelled lobes
stick out on the side and they cover up where
the legs would be moving underneath. Now you rotate at
ninety degrees, and then you've got another three sections. You've
got the head known as the cephalon, the middle section
known as the thorax, and the rear section known as
the pagidium. Now, one thing you might wonder, why do

(30:54):
we see these articulated segments on the shell of a trilobyte, Like,
why doesn't it have something more like a big solid
turtle shell? You know, why why the different plates overlapping? Well,
there are multiple answers, but one is that apparently some
TrailO bites were able to partially curl up and protect
their soft underbellies like an armadillo or a pillbug. Yeah

(31:19):
it so do you do you use the word pillbug
or roly poly? Do I think they're the same thing? Yes,
I believe the same creature or the same you know,
classification of creatures at the very least. But yeah, I
grew up with roly poly. I think I did too,
And somehow in my adulthood transition to pillbug, I've sold
out my childhood wonders. It does sound significantly less silly. Well, anyway,

(31:40):
trialo bite fossils are that. That's what you're walking on
in the Mount Stephen Trialo by beds, right, So you
walk around, you crunch through these things. You pick up
these rocks and they've got these little shells in them.
And the trio bite fossils are so common you can
get the sense that these animals must have been stacked
a mile high when they actually existed. Right, There were
a lot of them in the Cambrian but they're perhaps

(32:03):
overrepresented in the fossil record because many of the fossilized
shells we find are not the animals themselves, but the
discarded shells left over from the molting process. So, like
Arthur pods today, trial bites were himmed in by this
protective shell and if they wanted to grow bigger, they
had to molt, which meant discarding that protective outer layer.

(32:25):
And temporarily risking a soft bodied existence in order to
grow that larger, harder shell. It would be like if
there were a prehistoric hominid creature that left multiple skeletons,
you know, which is of course impossible, but with an
exoskeleton is is completely is very possible. Well, the vulnerability
of molting makes me think about the comparison to a

(32:46):
human newborn. You know, when when babies are born, they
don't necessarily have all their their hard protective skeletal parts yet,
and I have a lot of unfused together the unfused
skull for example, and the soft cartilaginous body arts where
you really do make yourself vulnerable when you're firstborn. But
of course they're depending on the fact that mammals have

(33:07):
protective parents that will try to prevent injury to their
offspring when they're young and vulnerable trialo bites. I don't
know if they're they're quite so protective of they're young.
I mean you could say that puberty is kind of
a molten period where where where we tend to be
soft and vulnerable, if not in if not in mentally,
at least mentally. Yeah. Uh so that's interesting to think

(33:29):
of the molten process having an impact on the sheer
number of fossilized remains. But but then on top of that,
of course, it makes you analyze, and we've discussed this
on the show before, like what makes a creature more
liable to be fossilized? And I mean, you look at
the creatures that are fossilized in any great number. It's

(33:49):
not going to be an apex predator living in a
dry region. It's going to be something like a low
level and burd invertebrate that lives in the muck. Yea
something that gets buried quickly. Uh, and that leaves behind
hard body parts near water, especially right. So the great
the Great Land squid of old rights have not been preserved,
but their beaks are many. Oh yes, that's right. We

(34:12):
would get the beaks, yeah, these beds of beaks, and
we'd wonder what they are. Yeah. But because there are
so many trialobite fossils, and because they're so strange and
so alien to the modern life forms we encounter in
our day to day lives, I mean, they might be
they might bear some resemblance to insects for example. Right,
And this is why railroad worker might call them stone bugs,

(34:32):
but it's no surprise that they show up in human
culture too. I wanted to mention one cool example I
came across. Remember Adrian Mayor who wrote the first Fossil Hunters.
We talked about her in our in our what was
it the geomethology? Yes, yes, this we had to do
with how did ancient people look at fossilized remains, didn't
think they were monsters? That they think they were dragons? Yeah? Yeah?

(34:54):
And did did these ideas of mythical monsters come from
people finding fossils? So she's got another boat called Fossil
Legends of the First Americans, and she writes of how
trio bite fossils were apparently used as protective amulets by
some of the Ute people of Utah. So this one
story is in the early nineteen hundreds, there was an
amateur natural historian named Frank Beckwith and he noticed a

(35:17):
trio bite necklace at a Ute burial site. So he
asked some friends of his name, Joseph and Tedford pick
of It, who were members of the tribe, what this meant,
and they told him that the fossil was called timpei
kanitsa Pavacci which meant little water bug in Stone and
Beckwith also records that the men told him that their
elders believed that wearing the trio bites could protect against

(35:40):
sickness and bullets. But I thought that's kind of cool that.
Look somehow the fossils were intuited to have been water
dwelling creatures, and I wonder how people would have figured
that out back then. I thought that was really interesting. Yeah,
especially given that there would be there would be plenty
of terrestrial invertebrates to compare it to. I guess maybe
they maybe they saw more of the of the crab

(36:04):
in this creature than they did, uh, you know, terrestrial bucks.
I know, I wouldn't have been that perceptive. I would
have called it like roly Poly or something. Well, anyway,
considering that all these there are all these shells everywhere,
another possible answer to the question of what caused the
Cambrian explosion comes up. What if the Cambrian explosion is

(36:25):
an illusion? What if it is not so much an
event in history where all these animals suddenly emerged, but
a misperception created by the types of evidence available to us.
So this would be like a reporting error exactly. It
would be a sampling bias. How would that be. Well,
like we've been talking about, we know fossilization has this

(36:45):
serious preference for hard body parts, and it appears to
be around the Cambrian period that biomineralization, right, the forming
of these mineral based body parts like skeletons and shells,
that that became common in many different animals. It's the
age of shells and exoskeletons. So it could be that
many animal forms had precedent in the Precambrian era, that

(37:08):
there were there were animals sort of like them living before,
and it's simply that we don't have good records of
them because they weren't making hard body parts yet. Okay,
so this makes sense. So it's not it's it's not
that just suddenly there are all these creatures around with
their hard shells. There were plenty of creatures around beforehand.
It's just those were not preserved. Those are not as
president the fossil record, right, because they didn't have the

(37:29):
hard shells. Yeah. On the other hand, even soft animals
leave some fossil traces like tracks and burrows, and generally,
I think paleontol just think that these types of fossils
are not as abundant as they would seem to be
if the Precambrian world was basically a soft flappy copy
of the Cambrian But either way, this leads us to

(37:52):
a kind of new way of framing the Cambrian question.
If the Cambrian explosion is characterized as this explosion of
animal body plans, and especially those with hard body parts,
why do the hard body parts show up? Like? Where
do they come from? Why evolve shells? And this leads
us to another possible answer to the to the cause
of the Cambrian explosion. What if it was caused by

(38:14):
a biological innovation like predation? Oh so like you, So
you have all of these creatures that have that have
evolved and then suddenly they realize, Hey, we can just
eat each other. I can I can just eat these guys.
Why should I compete for the same same meal when
I can make them my meal and then I'm essentially
eating what they already ate, Right? Why would I waste

(38:36):
my time filter feeding when I can just eat ted
over there? Yeah? So Eric Sperling, the Stanford paleontologist who
is the lead author on one of the papers I
mentioned earlier in this episode, he explained in a Nature
News article earlier this year, or actually know it was
last year, that he thinks a very modest increase in
dissolved oxygen could have been enough to push the the

(39:01):
ocean chemistry over the edge to allow for the emergence
of predation and carnivory as an ecological niche, which would
have thereafter driven evolution across the animal spectrum as this
arms race between predator and prey emerged. In a world
of predators, you need shells and you need to be
able to move. Yeah, alright, well, this this sounds the

(39:24):
sounds plausible, and there's some evidence that this is what
was happening. Here's an odd fact. Sometimes trialobyte fossils are
missing chunks, not because the fossils have been damaged, but
apparently because the animals were One example, a specimen of
the trial trialobyte illinoid is found in Walcott's Quarry at
the Burge of Shale, has this distinct W shape missing

(39:48):
from its left side, as if something took this kind
of two fanged bite out of it. So in this
alien ocean, and you have to imagine me uh in
the voice of ripley and aliens whose laying the eggs,
what's taking the bites out of these trilobites. Maybe it's
less dramatic if if you put it that way, but

(40:09):
but yeah, there's gotta be something something else out there,
some sort of predator that is that is chomping down
on these guys. And this leads us to the second
monster in our Cambrian monster house, the weird shrimp. All right,
hold that thought, because we're gonna take a quick break,
and when we come back, we will we will get
to know the weird shrimp, which is truly unless you're

(40:29):
already you know, super familiar with this time period, I
would say it's the first really alien creature of the
Cambrian period. Alright, we're back, Okay. So in a British
Canadian paleontologist named Joseph Frederick Witty Eves was trying to
figure out how to classify some odd Cambrian fossils that

(40:52):
looked like headless shrimp shells. You can look at pictures
of these online, but um, you could see these five
hundred million year old imprints of these clawed tails and bodies,
but the heads were always missing. Yeah, they look kind
of They basically looked like entrees. Yeah. Yeah, it's like
somebody pulled the head off the shrimp and served it

(41:14):
to you in a little cocktail glass. Now. He named
the organism Anomala carus, which means weird shrimp or strange
shrimp or odd shrimp, however you prefer. Meanwhile, Burgess Shale
pioneer Charles Walcott, which who is the guy who the
Walcott's Quarry at the Burgess Shield was named after, he
collected and described a fossil of a different animal. These

(41:37):
preserved remains only showed a large, disembodied mouth, a thick,
muscular ring shape surrounded by a circle of jagged teeth
facing inward. And Walcott believed this mouth to be the
remains of a jelly fish that he named Patoya. All right,
so this would be the mouth of an otherwise soft creature,
that was his argument. And all we have left is

(41:58):
the mouth, right. And it wasn't until many decades later
that researchers Harry Whittington and Derek Briggs figured out that
these two weird anomalous animals were weird and anomalous because
they were different parts of the same creature. A huge
Cambrian predator that retained the name of Anomala carus. The
weird shrimp were actually a pair of clawed appendages basically

(42:23):
mouth tentacles for snatching up prey and shoving it into
the mouth parts, and the mouth parts were the toothy ring,
which had previously been identified as patoya. If you've never
seen an image of Anomala cars this is another thing
to look up, well, or maybe we'll try to include
a picture on the landing. Yeah, we'll include a picture
of this this creature because it's just too it's too weird.

(42:44):
If if need be, we will draw one and uploaded
to the side. It's sort of like impossible to make
yourself believe that this thing really existed on Earth. But
I've seen the fossils now, and so the reason these
disembodied parts were originally is identified was a common problem
in paleontology. As we've mentioned several times now, fossilization is

(43:05):
strongly biased toward hard body parts like shells and bones.
Anomala Carus did not have a hard exoskeleton covering its
whole body, but probably had a very light, kitanous outer
layer like a shrimp shell. On some parts of its body,
and when it died and decomposed, its body probably fell
apart into different pieces, and not all of those pieces

(43:27):
were preserved at the same rate. So it's rare to
find fossils that preserve any information about soft body parts,
and even rarer still to find soft bodies intact, all
in one place. Rare, but not entirely impossible, because since
the original discovery of what amounted to Anomala cars is
killing equipment, more fully preserved Anomala Carus specimens have been discovered.

(43:51):
For example, one fossil discovered in nineteen two shows the
spiked feeding arms branching off of the head within reach
of the shing mouth ring, and all contained within the
imprint of this elongated soft body lined with lateral lobes
that probably undulated to power swimming. So if you're trying
to imagine this thing right now, you have to picture

(44:13):
a kind of wide, flat lobed jellyfish snake undulating along
through the ancient seas, with a gaping mouth ring on
the underside that could squeeze with teeth but never fully close,
and then sticking out of its face a couple of
hooked fang tentacles lined with spikes. Yeah, this this looks

(44:34):
like a creature that belongs in a Star Wars Cantina. Yeah. Yeah,
it should be like having a drink and telling you
it doesn't like you, and it probably doesn't like you.
Now you're you might be thinking, okay, so how big
were these things? Right? Like? A few inches long? Parts
found in fossil sites in China indicate that Anomalocarras type
organisms may have grown to almost two meters long, which

(44:57):
is around six feet. You know, people do those like
booking a swim with the dolphins thing. I think people
should book swim with the anomal of carrass. They should
use some kind of DNA engineering to bring these things
back well you know, and then have you swim with
them at the resort. Well, you know, the predation explosion
hypothesis is correct, especially, I mean, this was eating other

(45:20):
animals was a growth industry, so it it does make
sense that that the the successful model for eating other
creatures would produce larger and larger organisms, right. Yeah. So,
but the question I guess is if these things are
preying on the you know, the widespread trilobites of the
ancient seas, I don't know, would they take a bite
out of you if they could. So you're in the

(45:41):
water with them, you do obviously don't look or smell
like their normal prey, but then again, they might just
want to see what you taste like. It's hard to know.
We kind of get into that whole shark and gorilla area.
I don't know if I've mentioned this on the podcast,
but I don't think so. Well, every time I go
to the ocean, I comfort my self regarding the risk

(46:02):
or apparent risk of sharks and and of course just
shark media in general by thinking about the just like
a brief clip on The Simpsons where a shark jumps
out of the water and grabs a gorilla out of
a tree, which is ridiculous for several reasons, but it
drives home like this is this is something that does
not happen. Is not part of the the the the

(46:25):
the energy model for either species, you know. Uh, And
and that's essentially what I am. I am a gorilla
in the water, and the shark has not evolved to
eat me exclusively. It can if need be, but it's
not out there looking for gorillas, right. It might have also, though,
evolved a sort of like prey diversity, curiosity, it might
take a little nibble on you to see what you're like, right, right,

(46:47):
So I guess that would be the main concern. But
I'm guessing you would have this element of surprise because
by the way, I don't mean to be promoting like
fear of sharks. We're not their primary prey, right, But
but I'm guessing with with h means, if if we
were to go with our opening scenario and you were
just dropped into the waters among these things, I would
hope you would have this this element of surprise over them,

(47:10):
and they would be a bit shocked and uncertain and
hesitant to approach you. So another thing that's really cool
about Anomala carras is that they have these amazing eyes.
For a long time, detailed evidence of non biomineralized arthropod
eyes had been hard to find. But in two thousand
eleven there was a letter to Nature that detailed this

(47:30):
amazing find at the Emu Bay Shale of South Australia,
and what they had found was preserved Anomala carus eyes,
and they found that they had a pair of two
to three centimeter eyes about five fifteen million years old,
and they were compound eyes made of at least sixteen
thousand hexagonally packed lenses, meaning these eyes would have been

(47:52):
about as acute as the most powerful arthropod eyes today,
like dragonfly eyes. And the authors think that this is
that this evidence of acute vision lends support to the
idea that anomal a caress was a powerful, fast moving
apex predator going all throughout the water column, which and
this would have accelerated the arms race that triggered Cambrian

(48:14):
biodiversity and biomineralization. You know this also this makes me wonder, though,
would a creature like this have anything to fear? Well,
I mean probably not. I mean, if it's the apex
predator of an ancient ocean, what, it's the biggest thing
out there and it's got the most powerful killing equipment.
What does it have to worry about? Nothing? Until you know,
the time traveling human shows up and starts clubbing them.

(48:36):
I guess that club they brought. You'd have to bring
your own club. That's the key here. But nothing dead
will go. Ah, well, you know, maybe a still living
tree branch will work. Oh yeah, maybe that. Somebody should
have told kyleys about that. I guess that wouldn't have
been all that effective against the determinator. Yeah, where are
they going to get a tree branch and the desolate
post apocalypse future. Okay, we're on a tangent here, so

(49:00):
we're gonna look at some more uh Cambrian monsters. But
one more thing about anomally carriss before we move on.
There is still a fascinating debate going on about how
and what Anomala carress ate. So some of these wounded
trial bytes that we discussed earlier have injuries that really
seemed to match the two pronged grasping appendages of the
anomal carrass and some experts believe that its mouthparts would

(49:23):
not have been powerful enough to prey upon trial bytes
with their hard outer shells. So that kind of creates
a question like what was was it eating something else?
Like how could it have gotten through these hard outer shells?
There are a few options. Maybe maybe they were just
really beefy and they could crunch through those shells. Maybe

(49:44):
they had some method of prying the shells off of
weaker trialobytes and sucking up all the soft parts inside.
Or there's also an interesting possibility I learned about from
the guide on our hike, David. Maybe they took a
tip from the crab shack down the shore and they
sought out soft shells trial bytes who were in the
process of molting. So you you release your hard shell,

(50:07):
put that aside to be fossilized for people to find
millions of years later, and then you stay soft for
a little bit while you, you know, you grow. What
if they sought those out, the molten trial bytes and
nominomomb Oh man, Yeah, I mean that could be. That
could be the very uh niche that they are exploiting.
When you turn to the model of of of eating

(50:28):
other creatures, what better time than the molting period. Yeah, okay,
So the trial bytes and anomalo carras type creatures are
some of the main players that we see in UH
in Cambrian evolution, but there are also all of these
fascinating bizarre periphery organisms. Like Robert, would you like to
take us on a tour of the rest of the

(50:49):
Cambrian monster house. Sure? Yeah, we have some wonderful UH
specimens here to discuss here, and there's not there's not
necessarily as much data behind all of them. I mean
there's data, but it's maybe not as as sexy as
a trilobyte. However, they still have some some fascinating features,
and I think many of them would make excellent Halloween costomes.

(51:11):
I would say they're much sexier than the trilobyte, maybe
just not as a robust. So the first one here
I want to discuss is um opabinia. I've often called
the stock eyed vacuum cinabyte. That's a good description one
that I think evokes the alien qualities of this creature.
So if you're not looking at a picture of this

(51:33):
right now and stuff to blow your mind dot com,
I want you to imagine something like a shrimp orl lobster,
but with rows of side lobes along its sides, paddling
along like the ores of like a galley so spiking ship.
You's got these lobes on the sides, kind of like
we described with the nominal caras that undulate to move
it along throughout the water. Right And you know, it

(51:54):
is not that remarkable at the the end, Like I said,
if you were just catching it a glimpse of it
out of the corner of your eye, that the back
portion doesn't look that different from again, like a lobster
or shrimp or something. But it's the front end of
the creature that is is rather interesting because it has
a long, flexible proboscis tipped with grasping spines, and the

(52:15):
creature itself was about three inches long, not counting this
uh weird cool richie tentacle. Yeah, five eyes to right,
five eyes on stalks, yes, five eyes just standing right
at you on stalks like they put them on stalks.
It's like just a mess with us. Yeah, and I
think this all sounds very love crafty and but but

(52:36):
according to the Smithsonian National Museum of Natural History, a
reconstructed image of the creature resulted in laughter at a
nine two scientific meetings. So instead of looking at this
thing and thinking, oh, this sounds horrific, it's like, got
this reaching arm that you know is up to no
good with its spikes on the end. But yeah, apparently
when it was first presented, uh, other other scientists laughed

(53:01):
at the prospect of something this ridiculous looking. So you
have to think, So, it's got this reaching appendage that's
sort of like its mouth appendage thing, So what's sort
of like maybe sort of like an ant eater, I guess,
but it's obviously not a vertebrate, not a mammal. Yeah,
it was. The idea here is that this would have
haunted the soft seabed and it would have would have

(53:21):
reached into sand burrows with this, So this spiked terminating
wriggly arm to grab delicious worms and uh and actually
have a quote here. This is from HB. Whittington from
the enigmatic animal Opabinia regalis Middle Cambrian Burgess Shale, British Columbia.

(53:41):
This was presented the Royal Society b quote. Opabinia regalius
may have plowed shallowly in the bottom mud, propelled by
movement of the lateral lobes. The eyes are presumed to
have been capable of detecting movements in the surrounding waters,
and the frontal process to have been is to explore
the mud for food and bring it to the backward

(54:03):
facing mouth. The frontal process that is the most amazing
euphemistic term for killing equipment. And then they put the
frontal process through the thorax the way that my son
uh describes it with the animals when he's like drawing dinosaurs.
He says that this is the part that makes the
animal's eyes close and then die. Yeah, so you know,

(54:28):
the frontal process is the part that makes the trial
by its eyes closed. So this is this is the
cool specimen. It's it's unique, it's enigmatic, it's silly looking,
but it's also, you have to admit, a very sensible
organism when you really think about it. Um, it's it
needs something to grab those worms. It has a single
you know, grabber to do it. Now, it's also interesting

(54:51):
that this one remains unassigned to any other extinct or
currently living major group. That there are some theories, but
for most part, this is one of those um, you know,
abandoned prototypes you can think of. You know, there's there's
nothing out there that that we know of that is
a descendant of this thing. That's interesting because when I

(55:12):
think about organisms like this, I think about the relationship
between manipulation limbs and the evolution of intelligence. I mean,
there's one way of looking at the evolution of hominid intelligence,
and it's to say that, Okay, one thing that may
have driven humans and other you know, great apes to
have larger brains and more intellectual power than the average

(55:36):
mammal is that they've got free limbs that they don't
always have to use for walking and stuff like that
to manipulate objects, and that the manipulation of objects allowed
them to, you know, have advantages in the manipulation of
tools and stuff like that. Yeah, you can't help but
imagine like what if this had been a successful uh

(55:57):
limb of of of evolutionary ascension, and then it ended
up with all of these different like monolimbed creatures, you know,
plowing about in the seas, climbing up onto land and
maybe getting to the point where they're using that that
one spiky tentacle to to type on computer keyboards. Yeah, yeah,
you see it in octopy to you know, having these free,

(56:17):
these free limbs that they can manipulate things with. I
wonder could opabinia if it hadn't gone extinct yet, could
it have become the tool using creature before they were
even mammals. But instead it just remains this this weird
dead end that looks it looks like if you decided
to make an animal out of random Lego pieces and
you stuck that. I think they still have that that

(56:39):
sort of twisty grabber mechanism and the Lego kids today. Alright,
the next creature on our list. Here is the hallucigenia.
Hallucigenia well named. Yeah, it almost doesn't need a cool nickname,
but I know you have one thought up already. How
about the creeping headless spike worm. Yes, yeah, that's because

(57:02):
it works because we're essentially looking at a tube of
flesh with two rows of spines on one side and
one row of mouth tipped tentacles on the other, and
on either end, if we're keep in mind here we're
working from the fossils. Here on either end, there's kind
of a dark stain. Presumably one of them is the head.

(57:23):
And presumably the idea here is that, or at least
the early ideas that it walked about on those spines
and it waved its tentacles above it. Uh, so you
had this still walking tentacle waiver something with no modern analogy,
no modern analogy. It looks like something that you would
see illustrated in a Wayne Barlow alien book, you know, Yeah, yeah, absolutely,

(57:45):
or like something um, I don't know. It looks kind
of like one of those blobs that sometimes shows up
in a Gary Larson cartoon when he's just trying to
create a weird alien shape. Yeah, I mean it looks
like something that would come out of a dream, thus
its name. You know, it looks it's hallucigen you it's
something that is that that seems like a fever dream
of brought to life in a fossil. Now. I think

(58:06):
this was first first put together by paleontologists in the seventies,
right right, and then they had there was a subsequent
find from China that showed a similar creature with a
second row of tentacles tipped with claws, and then they realized, oh,
we have it upside down. The creature walked on the
tentacles and the spikes provided an upward facing protective array.

(58:29):
So that's a lot. I mean, it's still a weird
looking critter, don't get me wrong, but that's a lot
more in keeping us what we might expect. You know,
that's not that different from say a turtle with legs
on the bottom and the protective display on the top,
or any you know, various examples from the invertebrate world.
I don't know, is that less weird? I'm trying to think. Okay,
so it's it's like a worm and it's got these

(58:51):
long tentacles with mouths on them that it walks on. Yeah,
I mean, it's still weird and it's got spikes sticking up. Okay, yeah,
I guess a little less weirder than walking on the spikes. Yeah,
I guess. It's kind of a fun experiment you can
play anytime you see like a crazy alien illustration. Try
to decide is it more alien if you turn it
upside down? Uh? Because yeah, you can either improve upon

(59:13):
the design or figure out how they came up with
it to again with maybe. Alright, so let's talk about
it a little bit bit more here. So, University of
Durham invertebrate paleontologist Martin R. Smith, who is an interesting
chap He has a nice online presence. He placed the
fossil of one of these creatures in an electron microscope
in an attempt to figure out more about it, and

(59:37):
one of the pressing questions was name, like which which
end is the head and which one is the anus? Well, yeah,
I mean that that's sort of. I knew there was
some problem with locating its head, and that comes through
in my name nomenclature of it, the headless spike worm. Now,
I mentioned the stains earlier, right like, basically from the fossils.
We knew. We knew that there was like a big
stain on one end and a smaller stain on the other,

(59:57):
and one was presumably the head. So the larger stain
was was for a long time interpreted as a balloon
like head on this creature. But it turns out it
was very much a stain. It was the quote, decay
fluids that had been squeezed out of one end of
the guts of the organisms. Yeah, so this was the
anus and the head was on the other side. And

(01:00:19):
when they looked to the head, you know what, they
found hockey mask. Close they found a smiley face. Yeah,
a pair of eyes with a semicircular grin. Uh. And
so it was sort of like a they say, it
was sort of like a caterpillar looking creature. Yeah. Now
when I say smiley face, it's it's kind of abstract.
I'm looking at an image of it here. But but

(01:00:41):
we can't help but look at it with our with
our human failings and say, oh, well that's a smiley face.
Oh hallucigenia, you devil you. Yeah, so hallucigenia is a
fun one for sure. Stealing my heart, take me somewhere,
even weirder Robert, all right, well, the next one is
will Whack see a Boy? And uh, I believe you?

(01:01:03):
Did you? Did you come up with a name for
this one or did I? Okay, I think I actually
came up with a few different ones here. So it
looks kind of like a prehistoric iron maiden. It also
looks like an organic battle him or perhaps a grim
dark Pokemon, and it provides another splash of of the
bizarre to the Cambrian seas. So two rows of long

(01:01:26):
spines and a kind of plate mail armor of leaf
shaped ribbed plates again on something that looks like a hat.
It it looks like a spiked hat like plate mail
kind of scenario. I can't stress the armor analogy enough.
It's kind of like a half of a walnut with
with plate mail on it and knives sticking out. Yeah,

(01:01:48):
it looks like something an orc would wear on its head.
And uh, A lot of the fossils here are essentially
that we have of this thing are essentially flattened remains
of this natural armor. Again, it's the hard parts that
were left with and we just have to try and
interpret what the soft tissue would have consisted of. And
there are different interpretations here. Now, Martin Smith, who I

(01:02:10):
just mentioned earlier, he favors the mollus interpretation. He says
that their mouths, which would have been a radula bearing
two rows of teeth, have several similarities with the teeth
of modern mollus and uh and then they look nothing
like worm teeth. Because that's the other argument is that
these are essentially worm creatures. Specifically they would be bristle worms.

(01:02:32):
But that's more of a controversial interpretation. So there's not
a lot of depth for that particular organism other than
it just looks really strange. And when you when you
see illustrations of the Cambrian Sea, you will often find
it will get will get in there somewhere. It won't
be the central organism, but it will it will have
a place in the in the in the illustration. Now

(01:02:56):
I've got a question round, Yes, among this ancient Embrillan
monster house, this sea full of bizarre alien creatures, we
have to imagine that modern day life forms can trace
their roots back to organisms that inhabited these oceans, especially
when you think about very successful modern philo like vertebrates. Yeah,

(01:03:18):
because the whole idea here is not that like everything
dies often and life begins a new Uh, that some
of these models would would have descendants alive today, I'll
be rather different to organisms, and we have just such
a case with Pecaia. Though it's a controversial example, right, Yes, Yeah,
that this is not this is not set in stone

(01:03:40):
that the fossils, of course are. Yeah. You you referred
to this as the ancestor fish slug or potential potential ancestor.
So if you're not looking at an image of this creature,
imagine a sea slug that swims like a modern fish,
and you've got a clear vision of Pecaia, or at
least its clear vision as anyone. The crazy thing about

(01:04:03):
it is that that scientists point to its not a chord,
a precursor to the spinal cord, and also a key
aspect of this creature's swimming mechanics as a reason that
it could just be an ancestor of all vertebrates, including humans.
But we're also throwing a curve in all this because
it has a two lobed head that doesn't sound like
any vertebrates I've ever heard of. Yeah, scientists remain split

(01:04:26):
on this. Now. A nineteen discovery of a primitive fish
in the Lower Cambrian also suggests that it in Pekaia
had an even more ancient common ancestor. Okay, so it
might be that this thing wasn't a direct ancestor of
existing vertebrates, but that it might have been an offshoot
of whatever was a direct ancestor of living vertebrates. And

(01:04:48):
I think it will make a great Halloween costume for
anyone out there who's who's not sold on the previous specimens.
Grandma fish slug. Yeah, yeah, I mean I can just
imagine it moving like you get used to see ing
footage of sea slugs and uh similar creatures and the
way they move. But this would have moved if I'm
if I'm reading it correctly, more more like a fish,

(01:05:09):
more like an eel. So imagine like an eagle slug,
and that's what you have here totally. Now there's one more.
I I thought it would be good to mention because
it's got a slightly love crafty and face, right leon
Colia the Blind whip Hunter. Yes, it looks kind of
it's this one's kind of hard to explain really, but
you know, it looks shrimpy, looks a little flea like

(01:05:30):
but imagine a blind monster that stumbles around in the
murk just bull whipping everything in its vicinity with flails
and then just really whipping the heck out of potential prey,
so whips coming out of its face. Yes, and that's
what we have with leon Colia. Now we assume it
was blind because we haven't found evidence of I stalks yet,

(01:05:51):
which if the thing, of course is that given these
previous examples, it's entirely likely that that that could occur.
At some point a future fossil find will reveal, oh, well,
they did have eye structures and they look like this,
but for the time being, the ideas that they were
seemingly blind. The creature here was about two inches long,

(01:06:12):
and it's usually classified as an as an arthropod, though
sometimes it's thrown into the arachnomorph subgroups, which would connect it,
you know, more to scorpions in trilobytes. But still it's
a fascinating creature to try and imagine, especially in this
this changing time where eyesight is coming online for various

(01:06:33):
organisms and new new methods of exploiting other organisms are
becoming possible, and this one is just whipping things with
its face un fel it can eat something. Yeah, So
I guess that's going to have to conclude our tour
of the Cambrian monsters. But I do want to ask you, Robert.
So clearly we have not exhausted all of the fascinating

(01:06:54):
questions about the Cambrian period and the the emergence of biodiversity,
animal biodiversity, especially in the Cambrian periods. So I want
to ask you which of the Cambrian explosion theories we've
discussed today appeals to you the most. Obviously we haven't
covered all of the possibilities. There are other possible explanations
out there. But what what what? What strikes true to you? Like?

(01:07:17):
What sounds right? Does it? Could it have been site
as the thing that triggered all of this biodiversity, or
the innovation of predation and carnivary, or the chemistry for biomineralization,
or is it just this sampling bias where you know,
maybe that there isn't as much bio innovation in this
period as it seems just from the fossil record. I mean,

(01:07:38):
I guess I could play it safe and say a
little bit of all of those, but but I guess
I tend to buy more into the predation and and
cite arguments with some support by by by some of
the additional arguments. But but those are the two that
I guess I feel like they have the most meat
for me. But then again, I'm not a I'm not

(01:07:59):
a a scientist, you know, specializing in this time period.
But but those are the ones that I feel like
the most. Maybe it's just calling to the five year
old of me. It's the it's the explanation that involves
creatures warring with each other and battling each other, and
therefore that's the one that I can imagine. Yeah, it's
hard to resist, now, I know, I've I think I

(01:08:20):
read at some point that one of the arguments against
the site hypothesis is just that site doesn't generally matter
in the water, and especially in the deep water, as
much as it does on land. And not that it
doesn't matter at all, it does, but that you know,
things like smell and hearing and stuff like that are
more useful in the ocean. But yeah, I don't know,

(01:08:41):
I'm not sure which I'm most convinced by. The predation
one seems very interesting to me that if animals weren't
really capitalizing on getting their energy from other more large
sized animals before and suddenly they started doing that. That
that could be you know, a game changer. It's also
kind of an original sin type scenario too. It feels

(01:09:03):
very mythic, right like that that the first creature to
figure out that it can it can prey on its
fellow organisms. And how does that occur? Like obviously it's
it's not just a situation of one day, Uh this
this creature just takes a bite out of another one
Like it's going to be a more gradual process and uh,
you know, and I'm likely begins with some sort of

(01:09:24):
gray area of competition for food, like for instance, a
creature it becomes adapt at stealing food from either maybe
stealing food from its mouth, and what happens if you
steal food from another creature's belly? Yeah, you know, I
mean that That is the difficulty of this hypothesis is
you have to imagine what's the process that gets you
there by gradual evolutionary change, Even if it's geologically rapid,

(01:09:48):
it still would have been gradual in biological terms. Um,
trying to you know, go from an organism organisms that
are all basically vegetarian to some organisms eating other animals. Yeah, yeah,
Like another example that comes to mind, as of course,
animals that will consume their own young or their own eggs.
We've talked about, you know, the parental cannibalism to sort

(01:10:09):
of re absorb essentially lost energy, and how that could
seemingly be an avenue into the UH into inter predation,
because if you're absorbing your own biomatter back into yourself,
then it becomes a less of a leap to absorb
the biomatter of another. I can also see a scavenging
to predation route that maybe uh, the the gradual changes

(01:10:34):
that allow you to better and better extracts nutrition from
dead animals that you find on the bottom of the
ocean could eventually become useful in killing live animals right right.
Or you could just always do it and an angel
told you not to until a snake suggested otherwise, just
another possibility that could be it. Well, Robert, I don't

(01:10:55):
I don't get the feeling that we're done with the
Cambrian period. I think we may come back here in
the few true to explore some other scientific issues and
when there may be other things to discuss with the
Burdge of Shale as well. Yeah, and uh, and in general,
I'd love to do some more episodes in the future
regarding prehistoric creatures. I feel like this is something we
come back to time and time again, well at least
on what a bi monthly uh kind of pattern, I guess. So,

(01:11:19):
I mean it's it's the seven year old in me.
I've I've never gotten over how much I love dinosaurs
and other weird organisms that don't exist today. It's it's
part of my love for monsters, and it's part of
what keeps bringing me back to paleontology. All right, well,
we'll leave it at that, but in the meantime, definitely
check out Stuff to Blow your Mind dot Com. I'll

(01:11:39):
check out the landing page for this episode because again
I'm gonna try to try to include images, illustrations of
fossil representations, whatever I can find for each of the
organisms presented here, so you can have some additional visual
idea of what we're talking about. And I'll include links
back to some of our other episodes that have dealt
with prehistoric organisms. And if you want to get in

(01:12:01):
touch with us directly with feedback about this episode or
any other to suggest future episode topic. You can always
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(01:12:22):
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